The present invention relates to the field of anti-inflammatory substances and other substances which act by inhibiting binding to the intracellular domain of an interleukin-1 receptor (hereinafter "IL-1-R"), such as, for example, the p80, type I IL-1 receptor. More particularly, the present invention is directed to novel ligands which bind to the IL-1-R intracellular domain and to inhibition or modulation of signal transduction by this receptor.
Interleukin-1-.alpha. and interleukin-1-.beta. (herein collectively "IL-1") are cytokines which produce a wide range of cellular activities. IL-1 causes an inflammatory response, which can be beneficial, such as in mounting an immune response to a pathogen, or when overexpressed can lead to other detrimental effects of inflammation.
The cellular effects of IL-1 are initiated by the binding of IL-1 to its receptors (IL-1-Rs) on the surface of target cells. The isolation of polynucleotides encoding IL-1-Rs and variant forms of such receptors has been described in U.S. Pat. Nos. 4,968,607, 5,081,228, 5,180,812, in PCT Publication No. WO91/18982, and by Sims et al., PNAS, 86, 8946 (1989) (disclosing the p80, type I IL-1 receptor). Processes for purification of IL-1-Rs have also been disclosed in U.S. Pat. No. 5,296,592.
Native IL-1-Rs are characterized by distinct extracellular, transmembrane and intracellular domains. The primary purpose of the extracellular domain is to present a binding site for IL-1 on the outside of the cell. When IL-1 is bound to the binding site, a "signal" is transmitted to the inside of the cell through the transmembrane and intracellular domains, indicating that binding has occurred. Transmission or "transduction" of the signal to the inside of the cell occurs by a change in conformation of the transmembrane and/or intracellular domains of the receptor. This signal is "received" by the binding of proteins and other molecules to the intracellular domain of the receptor, resulting in the effects seen upon IL-1 stimulation.
While IL-1 binding by IL-1-Rs results in beneficial cellular effects, it is often desirable to prevent or deter IL-1 binding from causing other detrimental cellular effects. Although substantial effort has been expended investigating inhibition of IL-1 binding to the extracellular domain of IL-1-Rs, examination of binding of proteins and other molecules to the intracellular domain of IL-1-Rs has received much less attention.
However, ligands which bind to the IL-1-R intracellular domain have yet to be identified. It would be desirable to identify and isolate such ligands to examine their effects upon IL-1-R signal transduction and their use as therapeutic agents for treatment of IL-1-induced conditions. Furthermore, identification of such ligands would provide a means for screening for inhibitors of IL-1-R/intracellular ligand binding, which will also be useful as anti-inflammatory agents.